Plot with shaded standard deviation

I am having issue with both patch and fill function. I am not able to fill the space between 'y_values_upper' and 'y_values_lower' curves. Thanks in advance for the help.

Here it is my code:

% Import the data
% Prompt the user to choose a file
[filename, filepath] = uigetfile('*.txt', 'Select a text file');
file_name = filename;
remove = '.txt';
file_name_clean = strrep(file_name, remove, '');

%%
%ZP AVERAGE
plot_name = ['Average_' file_name_clean '.svg'];
% Import data from text file
opts = delimitedTextImportOptions("NumVariables", 6);
opts.DataLines = [2, 84];
opts.Delimiter = "\t";
opts.VariableNames = ["Count", "ZP1", "Count2", "ZP2", "Count3", "ZP3"];
opts.SelectedVariableNames = ["Count", "ZP1", "ZP2", "ZP3"];
opts.VariableTypes = ["double", "double", "string", "double", "string", "double"];
opts.ExtraColumnsRule = "ignore";
opts.EmptyLineRule = "read";
% Construct the full file path
file_path = fullfile(filepath, file_name);
ZpData = readtable(file_path, opts);
% Calculate averages and standard deviations
average_Zp = mean([ZpData.ZP1, ZpData.ZP2, ZpData.ZP3], 2, 'omitnan');
std_dev_Zp = std([ZpData.ZP1, ZpData.ZP2, ZpData.ZP3], 0, 2, 'omitnan');
% Plotting the data with logarithmic x-axis and error bars for averages and standard deviations
figure;
plot(ZpData.Count, average_Zp, '-', 'LineWidth', 2, 'DisplayName', 'Zeta Potential');
hold on;
% Define vectors for the patch
y_values_upper = average_Zp + std_dev_Zp;
y_values_lower = average_Zp - std_dev_Zp;
% Create shaded area for the upper standard deviation
plot(ZpData.Count, y_values_lower, 'Color', 'r', 'DisplayName', 'SD');
plot(ZpData.Count, y_values_upper, 'Color', 'r', 'HandleVisibility', 'off');
title('Zeta Potential');
xlabel('ZP (mV)');
ylabel('Total count');
grid on;
legend;
hold off; 
% Set x-axis limit starting from 0
xlim([-100, 100]);
% Set x-axis ticks every 10 values
xticks(-100:10:100);
% Set the minor ticks
ax = gca;
ax.XAxis.MinorTick = 'on';
ax.XAxis.MinorTickValues = -100:5:100;
% Find peaks in the average_Zp data
[peaks, peak_indices] = findpeaks(average_Zp);
% Find the maximum peak
[max_peak, max_index] = max(peaks);
% Get the corresponding x-value for the maximum peak
x_value_at_max_peak = ZpData.Count(peak_indices(max_index));
% Display the peak information
fprintf('Maximum Peak Value: %.2f\n', max_peak);
fprintf('Corresponding X-Value: %.2f\n', x_value_at_max_peak);
% Add text annotation for the maximum peak
text(x_value_at_max_peak, max_peak, sprintf('Max Peak at %.2f', x_value_at_max_peak), ...
    'HorizontalAlignment', 'left', 'VerticalAlignment', 'bottom');
% Create a new folder
folderName = 'zp_graph';
mkdir(folderName);
% Save the plot as an image file (e.g., PNG)
saveas(gcf, fullfile(folderName, plot_name));

Answer 1

[Voss]

It looks like your y_values_upper and y_values_lower are column vectors, so be sure to take that into account when creating the data for the patch. Something like this works:

% column vectors:
y_values_upper =  2*rand(25,1);
y_values_lower = -2*rand(25,1);
x = (1:25).';

% make the patch
figure
patch([x; flipud(x)],[y_values_upper; flipud(y_values_lower)],'g')

If they were row vectors, the syntax would be different:

% row vectors:
y_values_upper =  2*rand(1,25);
y_values_lower = -2*rand(1,25);
x = 1:25;

% make the patch
figure
patch([x fliplr(x)],[y_values_upper fliplr(y_values_lower)],'g')

[MARCO]

thanks a lot! with the first syntax it works!

I also implemented the opacity and removed the edge in this way:

patch([ZpData.Count; flipud(ZpData.Count)],[y_values_upper; flipud(y_values_lower)],'r', 'FaceAlpha', 0.15, 'EdgeColor', 'none', 'DisplayName', 'SD')

[Voss]

You're welcome! Looks good.